This invention relates in general to respirators and in particular to a new and useful respiratory system in which the flow of the ventilating gas for a closed circuit is controlled by a control member which directs gas into a feed part so as to induce the ventilating gas flow therethrough and through the closed circuit.
A respiration apparatus is known from German No. OS 31 19 814. During the inspiration phase, the jet nozzle mounted in the tracheal tube is supplied with high pressure gas pulses having a frequency which is above the natural breathing frequency, more particularly about 300 per minute. At the end of the inspiration phase, the system is switched over to the expiration phase. At the proximal end of the tracheal tube, a venturi tube is provided which is supplied from a servo gas source through an injector nozzle by which a needed underpressure is produced in the tracheal tube during the expiration phase. Such a respiration apparatus appears advantageous in that the proximal end of the tracheal tube is in permanent communication with the ambient atmosphere, so that a free exhalation is possible.
To be able to supply the necessary amount of breathing gas within the available pulse duration period, high discharge pressures at the jet nozzle and high peak loads are needed. Such high pressure jet nozzles produce considerable noise and are therefore disturbing.
The discharge effect of the jet nozzle produces a suction in the feed part, causing a displacement which may amount to a multiple of the breathing gas discharge of the jet nozzle. It is then difficult to prevent a reverse respiration without additional measures.